Cr 
SPONGES iu 
times in order to occupy all of these branches, and I have found a worm which 
measured nearly or quite two feet in length, living in a sponge not more than 
six inches in diameter. 
I consider this worm as a parasite inasmuch as it lives within the orifices 
of the sponge. It is possible, however, that it may not receive any nutriment 
from the sponge itself, nor from any substance that the sponge may absorb. 
The protection afforded by the sponge may be all that the worm desires, yet it 
must be in a great measure detremental to the sponge, for it occupies portions 
of the tubular system in which the water should circulate freely. The worms 
enter the sponges by boring into them from between their base and the rock on 
which they grow. 
The sponge most frequently attacked by this long sea worm, is the Logger- 
head Sponge, in fact, I never examined a living specimen of this species which 
did not contain one or more of these parasites. 
One of the most usual internal parasites of the Tube Sponge, is a small 
worm about .10 in length, which lies encysted ( that is, enclosed in a kind of 
sack, probably formed by the sponge ) in the sarcode, among the tubes of the 
water system. (See Fig. 3, D, 0, where I have given an example of this worm 
considerably enlarged ) So abundant are these intruders, that it is impossible 
to cut a sponge of this species { Tube Sponge ) in any direction without. en- 
countering one of them. 
Regarding the power which sponges have of encysting objects which have 
been introduced into the sarcode, we find that sand is often taken into the wa- 
er system, probably through the incurrent tubes. This sand appears to be 
